In a Samsung Galaxy S i9000 with Froyo the card achieved the following benchmarks:
SD Tools
Write 5.3MB / s
Read 9.6 MB / s
System Benchmark AnTuTu
Write 5.5MB / s
Read 9.6 MB / s
In Samsung Galaxy as a mass storage via USB connected to a PC with Win7,
reach write speeds of max. 4.26 MB / s.
To transfer larger amounts of data should already bring patience.
But there are also so many other things to do,
as staring at the progress bar.
I think one would be of the opinion,
psychokinetically influence to take on the transfer speed,
then provides this as good practice.